Thermal buckling and post-buckling analysis of a novel functionally graded concrete pavement considering joint stiffness degradation

This paper develops a theoretical model to investigate the thermal-induced buckling behavior of a novel functionally graded concrete (FGC) pavement structure. The proposed structure is composed of three homogeneous layers made of steel fiber rubber concrete (SRuC) and geopolymer concrete (GPC), with functionally graded layers inserted between them. The effective material properties of SRuC are estimated using the Eshelby-Mori-Tanaka method and the rule of mixtures, while the graded layers follow a sigmoid law distribution to achieve smooth and continuous material transition. Based on Timoshenko beam theory and the von Kármán geometric nonlinearity, the governing equations for thermal buckling and post-buckling response of the FGC pavement are derived. The influences of temperature gradient and initial imperfection are considered in the analysis, while a rotational spring is introduced to account for the stiffness degradation of the pavement joint. The differential quadrature method (DQM) combined with a direct iterative algorithm is employed to numerically solve the governing equations. Detailed comparisons are performed with existing results to verify the validity and accuracy of the proposed approach. Finally, the influences of the volume fraction index, rubber and steel fiber contents, layer thickness ratio, joint rotational stiffness and initial imperfection are systematically analyzed.